1. Field of the Invention
The present invention relates to a magnetic head which is used in a magnetic disk apparatus, a magnetic tape apparatus or the like, and more particularly to a thin-film magnetic head having a small flying height, which is suitable for high-density recording, and to a manufacturing method therefor.
2. Background Art
Accompanying an increase in recording density, to minimize what is known as spacing loss in a floating-type head used in a magnetic disk apparatus, the spacing between the disk and the magnetic head, that is, the flying height is constantly being reduced, and there is a desire to make this constant from the outer periphery of the disk to the inner periphery of the disk.
A magnetic head slider capable of meeting such a need has been proposed and put into practical use, this being a slider having a distinct shape that is designed based on aerodynamics.
A feature of this distinctly shaped slider is that is has a depression part known as a cavity, so that a pressure lower than the atmospheric pressure is generated, this also being known as a negative-pressure slider.
This type of cavity is difficult to manufacture using mechanical cutting and grinding as used in the past, and is generally manufactured using photolithography and dry etching processes.
The method of forming a distinctly shaped slider in the past will now be described, with reference being made to FIG. 2.
First, the magnetic head is processed to a bar shape which is illustrated as a row 1, as shown in FIG. 2(A).
The row 1 is then cut away from the thin-film head wafer and the air bearing surface, and processed to an appropriate pole depth.
Because processing each one of these one at a time would result in poor productivity, generally, ten to twenty or more are arranged in a row and adhered to a supporting sheet known as the base 2 for machining. The base 2, in addition to the sheet-like shape shown here, can be block-shaped, and can be made of aluminum, stainless steel, or ceramic or the like.
In consideration of a subsequent cutting operation, the block shape in particular is often used. A wax-based adhesive 3 is used to temporarily hold the row 1 to the base 2.
This adhesive is applied by rubbing a solid wax onto the base 2, which has already been heated to above the softening point of the adhesive, or by spin coating a wax which has been dissolved into an appropriate solvent. The row 1 is then pressed onto the wax-based adhesive 3, and the adhesive is gradually cooled to achieve adhesion. The adhered condition is shown in FIG. 2(B).
Next, an appropriate resist material is coated onto the row 1, and is subsequently exposed and developed, thereby obtaining a resist mask 5 that reflects the cavity pattern as shown in FIG. 2(C). Then, using a dry etching process such as ion milling, the part of the row 1 other than the masked parts is etched, so as to obtain the desired cavity shape.
Finally, by cutting away each individual head, magnetic heads having a distinctly shaped slider are completed. To peel the completed slider from the base, either heating is done again to above the softening point, or immersion is done into an organic solvent.
However, when the row is temporarily held as described above by using wax, because of the heat generated in the etching process, the wax often softens, resulting the air bearing surface being processed being stained by the wax-based adhesive 3, this hindering the achievement of the desired cavity shape, and in severe cases resulting in a peeling off and falling off of the row 1.
Additionally, because of the gas resulting from the vaporization of the wax, the etching speed is reduced, this representing a cause of variations.
Considering the thermal effect on the thin-film head when the thin-film head is attached to the base, it is not possible to simply raise the softening point of the wax, and it is generally necessary to limit the withstanding temperature of the thin-film head to 100 to 120.degree. C. or lower. Therefore, it is necessary to select the softening point of the wax in the region of 100.degree. C.
In order to achieve a practical etching speed in the dry etching process the substrate temperature is generally raised to nearly 100.degree. C., so that the above-noted "looseness" problem with the wax is an unavoidable one.
While it is possible to lower the output of the etching system to hold the substrate temperature in the region of 80.degree. C. so as to increase the yield, the resulting reduction in etching speed inevitably reduces productivity.
The present invention solves the above-noted problem, and provides a method capable of stable manufacturing of a high-precision slider with a distinct shape, the result being a contribution to the achievement of a high-recording-density magnetic disk drive.